It is known that there are only a few methods available as a practical matter for pumping/lifting of gravel slurries, particularly slurries containing cobbles or boulders; however, amongst the four methods known, there are serious disadvantages attendant to their use.
For example, the elevator and/or bucket lift is accomplished using hinged parts which are subject to considerable wear when used in the presence of sand and gravel. Further, in the elevator and/or bucket lift method, the ability to transport liquid is also limited by bucket size and shape and angular orientation.
While the second or conveyor lift method is less susceptible to abrasion wear, it nevertheless does not effectively transport the liquid portion of a slurry. Moreover, the steepness of the angle at which the lift can be used is also greatly limited, as the slurry does not adhere to the conveyor belt.
The third or centrifugal pump method is the most common method of transporting slurries; however, this method is encumbered by two disadvantages, both of which are overcome by using a hydraulic lift. The first disadvantage is that the geometrical design of the impellers and casing make it difficult to build a reasonable-sized pump that will handle large rocks. The second disadvantage is that the pump, which is large and requires an even larger driving motor, must be located at the slurry source. Accordingly, if pumping from a pit or well, the pump must be placed at the bottom, which may be logistically difficult.
The fourth or standard hydraulic lift method has no moving parts, can be built to handle large-sized solid material such as rocks, and can be located remotely from its power source; however, two prominent disadvantages encumber this method. The first disadvantage is that the mixing section of the lift is typically a rigid abrasive-resistant material that will not yield if a rock gets wedged in that section. The second disadvantage is that the efficiency of the lift and the maximum lift height attainable are directly related to the inside diameter of the mixing section. Therefore, when the mixing section size is increased to accommodate larger rocks or other solid particles, both the performance and efficiency decrease.
There is a need to overcome the disadvantages attendant to the standard hydraulic lift method; namely: 1) to resolve the fact that the mixing section of the lift will not yield if a rock gets wedged in that section due to the rigid nature of the abrasive-resistant material of the mixing section; and 2) to overcome the encumbrances that the efficiency of the lift and the maximum lift height attainable are directly related to the inside diameter of the mixing section (for example, if the mixing section size is increased to accommodate larger rocks or other solid particles, both the performance and efficiency decrease).